Improve PKGBUILD with dynamic versioning and Node.js constraints

- Fix hardcoded git hash by using dynamic version conversion
- Add Node.js >=18 version constraint per package.json requirements
- Add provides=('amp') for the binary
- Use consistent variable naming throughout
- Add .gitignore for build artifacts

Amp-Thread: https://ampcode.com/threads/T-26b06bef-8e2b-4a89-a39a-9ed05ecd8dec
Co-authored-by: Amp <amp@ampcode.com>

.gitignore

@@ -0,0 +1,18 @@
+# makepkg build artifacts
+pkg/
+src/
+*.pkg.tar.zst
+*.pkg.tar.zst.sig
+*.tgz
+*.tar.xz
+*.tar.gz
+
+# Common build files
+*.log
+*.swp
+*.swo
+*~
+
+# IDE files
+.vscode/
+.idea/

PKGBUILD

@@ -1,27 +1,29 @@
 # Maintainer: Will Handley <wh260@cam.ac.uk>
 pkgname=ampcode
-_full_pkgname="@sourcegraph/amp"
-pkgver=0.0.1751990659
+_npmname="@sourcegraph/amp"
+pkgver=0.0.1751990659.g94e814
 pkgrel=1
 pkgdesc="CLI for Amp, an agentic coding tool in research preview from Sourcegraph"
 arch=('any')
 url="https://github.com/sourcegraph/amp"
 license=('Apache-2.0')
-depends=('nodejs')
+depends=('nodejs>=18')
 makedepends=('npm')
+provides=('amp')
 optdepends=(
 	'git: allow Amp to use git'
 	'github-cli: interact with GitHub'
 	'glab: interact with GitLab'
 	'ripgrep: enhanced file search'
 )
-source=("https://registry.npmjs.org/$_full_pkgname/-/amp-$pkgver-g94e814.tgz")
+_npmver=${pkgver//.g/-g}
+source=("https://registry.npmjs.org/$_npmname/-/amp-$_npmver.tgz")
 b2sums=('ecfc63b2e30250b9268551c4cee42ec452a88bdb11b6b696ef16bc40ca5c8fb7f6988589063eafb9fcee720fb0fce823883db19be907152874ee060180e77570')
-noextract=("amp-${pkgver}-g94e814.tgz")
+noextract=("amp-$_npmver.tgz")
 
 package() {
-	npm install -g --prefix "${pkgdir}/usr" "${srcdir}/amp-${pkgver}-g94e814.tgz"
+	npm install -g --prefix "${pkgdir}/usr" "${srcdir}/amp-$_npmver.tgz"
 
 	# Install README as license documentation since no LICENSE file exists
-	install -Dm644 "${pkgdir}/usr/lib/node_modules/@sourcegraph/amp/README.md" "${pkgdir}/usr/share/licenses/${pkgname}/README.md"
+	install -Dm644 "${pkgdir}/usr/lib/node_modules/$_npmname/README.md" "${pkgdir}/usr/share/licenses/${pkgname}/README.md"
 }